Rooting Out DNS Errors

DNS misconfigurations and similar problems are a major source of ISP angst. DNS Expert Pro 1.5.1 can relieve the stress.

by Rich Santalesa

Think configuring DNS server settings is a one-time, set-and-forget operation? Think again. On a popular list covering mail servers, DNS-related problems, questions, and situations pop up again and again. As one member quipped, "I deal with customers' NT-networks all day, and know a lot about IP and NT, but I didn't realize I'd have to be a DNS expert, too."

DNS mappings underpin the entire Internet, so when a customer calls because s/he suddenly can't send email—even though the mail server's running fine—or you can't reach a web site you know has to be up, don't chalk it up to Internet voodoo, check your DNS servers first.

DNS chaos
According to an August 1999 survey by Men and Mice, of 5,000 randomly selected Internet zones, 73.3 percent had one or more incorrect DNS configuration issues, the most common setup error being incorrect name server delegation. Personally I've found that incorrectly configured secondaries and reverse in-addr.arpa problems are also rampant. For example, if in trying to download a 128-bit version of IE or Netscape your IP can't be verified as being within the U.S. you've run into one type of common reverse mapping error.

While there's no substitute for spending quality time with the various DNS-related RFCs or hunkering down to study O'Reilly & Assoc.'s classics, DNS on Windows NT or DNS and BIND, reaching for a copy of DNS Expert Professional 1.5.1 from Men and Mice is just what the doctor ordered for stamping out DNS-related outbreaks.

At $295 DNS Expert Pro 1.5.1 is a bargain for anyone responsible for DNS set-ups or maintenance of multiple domains. A $99 Standard version of DNS Expert is functionally identical, except that it can only test one domain at a time.

Four-in-one = DNS fun
To pinpoint misconfigured DNS entries, identify security problems, and test the general the general health of Internet connections and DNS servers, DNS Expert Pro is divided into four main diagnostic areas:

• DNS Zone Analyzer
• DNS Query
• Ping Host
• Trace Route to Host.

The bulk of DNS Expert Pro's heavy diagnostic work takes place in the DNS Zone Analyzer tool. Click the Zone Analyzer button, then enter a list of domains to scour. Next, select the type of analysis to perform "(minimal," "normal," "thorough," or one of your saved customized analysis settings), and let DNS Analyzer rip.

Depending on the testing level selected, DNS Analyzer conducts up to 68 tests in ten categories: Delegation, Security, A, CNAME, MX, NS, SOA, HINFO, and PTR records, and a batch of miscellaneous tests not covered in the other areas.

As it cranks along Analyzer provides a running summary of its findings in a separate window, listing the number of warnings and errors discovered. Once Analyzer finishes testing each domain, you can double-click on the domain (while testing of other zones continues), to pop-up a list of the specific errors and warnings. Very handy reports can be previewed on screen or printed in either summary or detail forms.

go to Page 2: Fixing as well as finding